Pasteurization is the process of heat-treating certain foods and beverages to destroy pathogenic microorganisms. It's named for the French scientist Louis Pasteur, who in the 1860s demonstrated that abnormal fermentation of wine and beer could be prevented by heating the beverages to about 135° F(57° C) for a few minutes. Heating fresh or "raw" milk removes 99.9% of all bacteria from the milk and extends it's shelf life.

The most common method of pasteurization in the United States today is High Temperature Short Time (HTST) pasteurization, which raises milk temperatures to at least 161° F for not less than 15 seconds, followed by rapid cooling.

For a product to be considered Ultra Pasteurized (UP), it must be heated to not less than 280° F for two seconds. Ultra pasteurization results in a product with longer shelf life but it still requires refrigeration. Ultra Pasteurized milk is so radically altered that it is not suitable for cheesemaking.

For best quality, raw milk must be heated slowly during pasteurization. Below, you will find recommended methods of heating raw milk and eggnog, a variety of pasteurization temperatures and their corresponding heating times.

How To Pasteurize Fresh Milk On The Stove Top

Use a double boiler or place a small saucepan inside a large pan.

Step1. Put water in the bottom pan and bring it to boiling. Pour the raw milk into the top pan. Heat it over the boiling water, stirring constantly.

Step 2.Use a meat or candy thermometer to determine when the temperature reaches the desired temp and keep it at this temperature for required time(see below).

Step 3*. Set the pan of hot milk in a container of cold water(or an ice cream maker works well too!). Keep the water cold by adding ice. Continue to stir until the milk is cold, then store between 35 and 45 degrees Fahrenheit(or in the refrigerator).

Pasteurize Fresh Milk Using A Microwave Oven

Step 1. Heat to temp using a temperature probe.

Step 2. Stir the milk once or twice during the heating period to equalize the temperature throughout. Cool as directed above*.

Fresh Milk Pasteurization Temperature Guide

If the fat content of the milk product is 10 percent or more, if it contains added sweeteners, or if it is concentrated (condensed), the specified temperature should be increased by 5ºF(3ºC).

Temperature Time Pasteurization Type

145ºF(63ºC) 30 minutes Vat Pasteurization

161ºF(72ºC) 15 seconds High Temperature - Short Time Pasteurization(HTST)

280ºF(138ºC) 2 seconds Ultra Pasteurization(UP)

Eggnog Pasteurization

Eggnog should be heated to at least the following temperature and time specifications:

TemperatureTimePasteurization Type

155ºF(69ºC) 30 minutes Vat Pasteurization

175ºF(80ºC) 25 seconds High Temperature - Short Time Pasteurization(HTST)

180ºF(83ºC) 15 seconds High Temperature - Short Time Pasteurization(HTST)